Recently, wide-band transmission using a millimeter wave band is attracting attention as one way of transmitting broadband signals with high quality. Particularly, radio waves of the millimeter wave band (for example, 60 GHz) have short wavelengths, leading to possible miniaturization of apparatuses, and have the physical property such that the radio waves do not reach a far distance due to their large oxygen-originated absorption attenuation, so that interference is not likely to occur. For this reason, various modes of usage as radio communication systems which realize mass transmission at a low cost are expected.
A possible use mode of the radio communication system using the millimeter wave band in an office is a so-called short-distance desktop radio communication system in which terminal units, such as personal computers (PCs), are placed facing one another on a desk in a conference room or the like, and transmit and receive radio signals via antennas provided at the respective terminal units.
By the way, in such a short-distance desktop radio communication system, a radio signal transmitted from one terminal unit may be reflected at a wall, a ceiling or the like to be received by other terminal units. Especially, a radio signal may be reflected multiple times at walls or a ceiling to be received by other terminal units. That is, the propagation paths from one terminal unit to the other terminal units become a so-called multipath (multiplex transmission path), which deteriorates the transmission quality, may eventually cause a data error. When designing those short-distance desktop radio communication systems, therefore, modeling of adequate propagation paths becomes essential.
Conventionally, various studies have been made on modeling of propagation paths especially in consideration of a multipath. For example, Non-patent Document 1 proposes an SV (Saleh-Valenzuela) model on the assumption of the use of a non-directional antenna and over-the-horizon communication. In addition, with regard to this SV model, there have been proposed a model which has an angular dispersion parameter of a delayed wave added as disclosed in, for example, Non-patent Document 2, and a model which extracts the dispersion state of the amplitude of a delayed wave as a parameter as disclosed in Non-patent Document 3.
Non-patent Document 1: Adel A. M. Saleh, Reinaldo A. Valenzuela, IEEE Journal on selected areas in communications. Vol. SAC-5, No. 2, February 1987.
Non-patent Document 2: Quentin H. Spencer, Brian D. Jeffs, etc., IEEE Journal on selected areas in communications. Vol. 18, No. 3, March 2000
Non-patent Document 3: Chia-Chin Chong, Su Khiong Yong, IEEE Transactions on Antennas and Propagation, Vol. 53, No. 8, August 2005